It is known to construct sensing edges of a flexible elongate sheath with an elongate inner core positioned therewithin, such that a chamber, which is generally U-shaped in cross section, is formed between the inner core and the sheath. Complementarily positioned within the U-shaped chamber is a standard compressible switch. The switch is comprised of a pair of compressible foam layers which sandwich a perforated foam layer. A pair of flexible, electrically conductive contacts are interposed between the perforated layer and the compressible layers, such that upon application of force to the sheath, a portion of at least one of the sheets of electrically conductive material deflects into a perforation of the perforated foam layer of material and makes electrical contact with the other of the sheets of electrically conductive material to thereby actuate the device.
In the sensing edge field, customers often require that the sensing edges have a certain sensitivity which may vary from customer to customer depending, in part, upon the desired end use of the sensing edge. In order to meet the requested sensitivity of the sensing edge, the elastic compressibility of each of the foam layers must be individually selected as well as the size and number of the perforations in the perforated layer, because the inner core is constructed of a substantially rigid material. Accordingly, a significant amount of downtime in the manufacturing process is incurred every time a change in sensitivity is required from the sensing edges then being produced. Hence, a need has arisen for the ability to change the sensitivity of the sensing edges being produced in a quick and efficient manner without incurring a significant amount of manufacturing downtime.
The present invention is directed to a sensing edge wherein the sensitivity thereof can be readily changed. The sensitivity of the sensing edge in accordance with the present invention can be readily changed by merely changing the elastic compressibility of the inner core thereof. Consequently, the present invention overcomes the problems inherent in the manufacturing of prior art sensing edges by changing the elastic compressibility of a single element of the sensing edge which results in considerable savings of money and time in the manufacturing of the sensing edge.